Sulfur oxides (SOx) such as sulfur dioxide are contained in discharge gases generated by thermal power stations; plants such as chemical-production plants, metal-processing plants, sintering plants, and paper-making plants; and gas turbines, engines, incinerators, and similar facilities provided with a boiler employing a fuel such as coal or heavy oil. Thus, a flue gas processing apparatus is employed in order to remove SOx contained in discharge gases. Such a conventional flue gas processing apparatus removes SOx contained in a discharge gas, by causing SOx to be adsorbed by a porous carbon material such as activated carbon fiber, oxidizing a sulfur component by oxygen contained in the discharge gas in the presence of the porous carbon material serving as a catalyst unit, and absorbing the oxidation product in water, to thereby form sulfuric acid, which is removed from the porous carbon material.
However, the aforementioned conventional flue gas processing apparatus including a catalyst unit formed of porous carbon material has the problem that its processing efficiency is low. In order to solve the problem, there has been proposed a flue gas processing apparatus containing a catalyst unit formed of plate-like activated carbon fiber sheets and corrugated activated carbon fiber sheets, which are alternatingly juxtaposed. In the apparatus, water is added dropwise to activated carbon fiber contained in the catalyst unit, and a discharge gas is caused to pass through conduits provided between the sheets, whereby a sulfur component is effectively removed in the form of sulfuric acid. However, there remains a demand for further enhancement in processing efficiency of the above flue gas processing apparatus.
In order to meet the demand, an object of the present invention is to process sulfur oxides at higher efficiency.